Few-Body Systems

, Volume 47, Issue 4, pp 213–224

Three-Body Spectrum of 18C and its Relevance to r-Process Nucleosynthesis

  • A. Yakhelef
  • N. K. Timofeyuk
  • J. S. Al-Khalili
  • I. J. Thompson
Article

Abstract

The 18C spectrum has been studied in a three body n + n +16C model that includes deformation and the 2+ excitation of the 16C core as well as Pauli projection of forbidden states. The 16C – n interaction employed in this study has been fitted to reproduce the experimental spectrum of 17C. The calculations show that two neutron separation energy in 18C in consistent with three-body structure of this nucleus and predict more states bound with respect to three-body decay. The comparison of their position to known excited states in 18C is discussed. These calculations suggest also that a few states may exist in astrophysically relevant region between the 17C+n and 16C + 2n decay thresholds. The most important of them is 1 as it can give a large E1 resonant contribution to 17C(n, γ)18C neutron capture. The calculations also suggest that a virtual s-wave state may exist above the 17C + n threshold that can give rise to non-negligible M1 contributions to the 17C(n, γ)18C reaction rate. The presence of these states in the 18C spectrum can lead to an increased 17C(n, γ)18C reaction rate, which can significantly influence the abundances of uranium and thorium synthesized in the r-process in the supernovae explosions.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Sasaqui T. et al.: Sensitivity of r-process nucleosynthesis to light-element nuclear reactions. Astrophys. J 634, 1173 (2005)CrossRefADSGoogle Scholar
  2. 2.
    Herndl H. et al.: Reaction rates for neutron capture reactions to C, N, and O isotopes to the neutron rich side of stability. Phys. Rev. C 60, 064614 (1999)ADSGoogle Scholar
  3. 3.
    Warburton E.K., Brown B.A.: Effective interactions for the 0p1s0d nuclear shell-model space. Phys. Rev. C 46, 923 (1992)ADSGoogle Scholar
  4. 4.
    Elekes Z. et al.: Low-lying excited states in 17,19C. Phys. Lett. B 614, 174 (2005)ADSGoogle Scholar
  5. 5.
    Stanoiu M. et al.: Disappearance of the N = 14 shell gap in the carbon isotopic chain. Phys. Rev. C 78, 034315 (2008)ADSGoogle Scholar
  6. 6.
    Ong H.J. et al.: Lifetime measurements of first excited states in 16,18C. Phys. Rev. C 78, 014308 (2008)ADSGoogle Scholar
  7. 7.
    Kondo Y. et al.: One-neutron removal reactions of 18C and 19C on a proton target. Phys. Rev. C 79, 014602 (2009)ADSGoogle Scholar
  8. 8.
    Horiuchi W., Suzuki Y.: Erratum: Structure of and E2 transition in 16C in a 14C + n + n model. Phys. Rev. C 73, 037304 (2006)ADSGoogle Scholar
  9. 9.
    Hagino, K., Sagawa, H.: Three-body model calculations for the 16C nucleus. Phys. Rev. C 75, 021301(R) (2007)Google Scholar
  10. 10.
    Imai N. et al.: Anomalously hindered E2 strength \({B(E2;2_1^+ \to 0^+)}\) in 16C. Phys. Rev. Lett. 92(6), 062501 (2004)CrossRefADSGoogle Scholar
  11. 11.
    Maddalena V. et al.: Single-neutron knockout reactions: application to the spectroscopy of 16,17,19C. Phys. Rev. C 63, 024613 (2001)ADSGoogle Scholar
  12. 12.
    Nunes F.M., Christley J.A., Thompson I.J., Johnson R.C., Efros V.D.: Core excitation in three-body systems: application to 12Be. Nucl. Phys. A 609, 43 (1996)ADSGoogle Scholar
  13. 13.
    Thompson I.J., Danilin B.V., Efros V.D., Vaagen J.S., Bang J.M., Zhukov M.V.: Pauli blocking in three-body models of halo nuclei. Phys. Rev. C 61, 024318 (2000)ADSGoogle Scholar
  14. 14.
    Karataglidis S., Amos K., Fraser P., Canton L., Svenne J.P.: Constraints on the spectra of 17,19C. Nucl. Phys. A 813, 235 (2008)ADSGoogle Scholar
  15. 15.
    Ridikas D. et al.: Exploratory coupled channels calculations for loosely bound carbon isotopes. Nucl. Phys. A 628, 363 (1998)ADSGoogle Scholar
  16. 16.
    Gogny D., Pires P., De Tourreil R.: A smooth realistic local nucleon-nucleon force suitable for nuclear Hartree-Fock calculations. Phys. Lett. 32 B, 591 (1970)ADSGoogle Scholar
  17. 17.
    Van Rij W.I., Hess C.T.: The deformed spin-orbit potential in Nilsson-model calculations. Nucl. Phys. A 142, 72 (1970)ADSGoogle Scholar
  18. 18.
    Danilin B.V., Thompson I.J., Vaagen J.S., Zhukov M.V.: Three-body continuum structure and response functions of halo nuclei (I): 6He. Nucl. Phys. A 632, 383 (1998)ADSGoogle Scholar
  19. 19.
    Bohr A., Mottelson B.R.: Nuclear Structure, vol. II: Nuclear Deformation. Benjamin, New York (1975)Google Scholar
  20. 20.
    Datta U. et al.: Coulomb breakup of the neutron-rich isotopes 15C and 17C. Phys. Lett. B 551, 63 (2003)ADSGoogle Scholar
  21. 21.
    Batham P., Thompson I.J., Tostevin J.A.: Dynamical core deformation effects on single-nucleon knockout reactions at fragmentation beam energies. Phys. Rev. C 71, 064608 (2005)ADSGoogle Scholar
  22. 22.
    Elekes Z. et al.: Decoupling of valence neutrons from the core in 16C. Phys. Lett. B 586, 34 (2004)ADSGoogle Scholar
  23. 23.
    Bazin D. et al.: One-Neutron Halo of 19C. Phys. Rev. Lett. 74(18), 3569 (1995)CrossRefADSGoogle Scholar
  24. 24.
    Brown, B.A., Rae, W.D.M.: NUSHELL@MSU, MSU-NSCL Report, 2007 (unpublished)Google Scholar
  25. 25.
    Simpson E.C., Tostevin J.A.: One- and two-neutron removal from the neutron-rich carbon isotopes. Phys. Rev. C 79, 024616 (2009)ADSGoogle Scholar
  26. 26.
    Chatterjee R., Okolowicz J., Ploszajczak M.: Description of the 17F(p, γ)18Ne radiative capture reaction in the continuum shell model. Nucl. Phys. A 764, 528 (2006)ADSGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • A. Yakhelef
    • 1
  • N. K. Timofeyuk
    • 2
  • J. S. Al-Khalili
    • 2
  • I. J. Thompson
    • 3
  1. 1.Physics DepartmentUniversity Farhat Abbas-SefifSetifAlgeria
  2. 2.Physics DepartmentUniversity of SurreyGuildfordUK
  3. 3.Lawrence Livermore National Laboratory, L-414LivermoreUSA

Personalised recommendations